Rotor cooling device in an oscillation type compressor

ABSTRACT

A rotor cooling device for an oscillation type compressor, wherein one end of the rotor is extended axially along the axis of rotation thereof. The extended portion of the rotor is surrounded by a housing in which a cooling liquid injection means and a cooling liquid discharging means are provided. The rotor is provided with an axial hole in the central portion thereof through which cooling liquid is supplied from said injection means and discharged by the discharging means for cooling the rotor.

[451 Aug. 6, 1974 ROTOR COOLING DEVICE IN AN 2,027,594 l/l936 418/94 X OSCILLATION TYPE COMPRESSOR 2,557,497 6/l95l Carney........................... 4l7/DIG. l

Nozom., Jinkawa, Akashi, Japan FOREIGN PATENTS 0R APPLICATIONS United States Patent [191 .Hinkawa [75] Inventor:

PATENTEnms slm 'FIG. 2

ROTOR COOLING DEVICE IN AN OSCILLATION TYPE COMPRESSOR This is a Continuation, of application Ser. No. 231,932, filed Mar. 6, 1972, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a cooling device for a compressor, and more particularly, to a system for cooling a rotor of a oscillation type air compressor.

DESCRIPTION OF THE PRIOR ART In an oscillation type compressor in which a rotor is oscillated in a cylinder, the rotor is completely lubricated at the bearings thereof. The radial edges of the rotor are provided with sealing material, such as carbon or tetra fluoro ethylene, so that the end of the rotor vanes will not be in direct contact with the inner surface of the cylinder. Thus, there is no need to provide lubrication oil in the cylinder in this type of compressor as is required in the ordinary reciprocation type compressor. Thus, this type of compressor can be or considered to be an oil-free compressor.

However, this type of compressor has difficulties with abrasion of the sealing material which is in contact with the outer surface of the central part ofthe rotor. As the discharge pressure of the compressor is increased, the temperature of the air is increased. Since the construction of the rotor is not designed to be water cooled, the temperature of the rotor is greatly increased as the discharge pressure rises and abrasion of the sealing material which is in contact therewith is drastically accelerated. l

SUMMARY OF THE INVENTION In light of the above-noted defects of the conventional oscillation type compressor, the primary object of the present invention is to provide a cooling system for cooling the rotor of an oscillation type compressor.

Another object of the present invention is to provide a rotor cooling system for an oscillation type compressor in which the rotor is cooled to such a temperature that the abrasion of the sealing material is prevented.

Still another object of the present invention is to provide a rotor cooling system for an oscillation type compressor in which the compressed air in the cylinder is also cooled by contacting the surface of the rotor and the temperature of the discharged air is, accordingly lowered.

In order to accomplish the above objects, the rotor in the compressor is provided with an axial hole extending axially through the center thereof for introducing cooling fluid thereinto.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a transverse cross-sectional view of the compressor in accordance with the present invention, and

FIG. 2 is a longitudinal sectional view taken along the line lI-Il in FIG. 1.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENT Referring to FIG. l, a rotor 3 having vanes 3a and 3b is rotatably supported in the bore of a cylinder l. The rotor 3 is provided at the radial ends of vanes 3a and 3b with sealing material 2 such as carbon or tetra fluoro ethylene in sliding 'contact with the inner surface bore of the cylinder l. A pair of inlet valve seats 7 are fixed to the cylinder 1 on opposite sides of the rotor 3. In FIG. 1, a pair of sealing material pieces 5 are disposed on the valve seats 7 in contact with the outer peripheral surface of the rotor 3. Air is introduced into the cylinder 1 through inlet passages 4 and inlet valves 6. Compressed air is discharged out of the cylinder through discharge valves 8 and discharge valve boxes 9. The cylinder l has a water cooling jacket construction so as to be maintained at comparatively lower temperatures.

Referring now to FIG. 2, one end (the right end in the embodiment shown in the drawings) of the rotor 3 is extended outward from the bearing 11 in the axial direction and is provided with an axial hole or bore 19 along the longitudinal axis thereof extending from said one end. A housing 20 encloses the extended portion of the rotor 3, and has a cooling liquid injection pipe 24 extending coaxially with and into the hole 19. Also, a cooling liquid discharging pipe 26 is provided on the housing 20. In FIG. 2, a bearing l0 is disposed on the opposite end of said extended portion of the rotor 3, with the rotor also being extended leftward. A pin 12 and an arm 13 are provided for interconnecting the rotor with a driving means. Sealing cylinders or sleeves 14 and 15 for partitions 16 and 17 are provided at the opposite ends of the rotor 3. An inlet duct 18 is connected with said inlet passages 4, and a pair of seal rings 21 are interposed between the extended end portion of the rotor 3 and the housing 20 with a slight space therebetween as illustrated in FIG. 2. In the space, the peripheral wall of the housing 20 is provided with a drain hole 22 for precluding cooling liquid from entering the bearing l1. This drain hole 22 is provided for the purpose of precluding the cooling liquid from entering into the bearing 1l around the left seal ring 2l even if there is leakage into the space between the rings 21 over the right seal ring 21. An external cooling liquid supply tube 25 is connected with said cooling liquid injection pipe 24 outside the housing 20.

In operation, a cooling medium is supplied into the injection pipe 24 from the external supply tube 25 and the cooling medium or liquid is introduced into the axial hole 19 at the left end thereof and flows rightward in the hole 19 cooling the central portion of the rotor 3 and is discharged out of the housing 20 through the discharge pipe 26.

Thus, the rotor 3 is positively cooled by a cooling means, and accordingly, the temperature of the rotor is not increased as much as in the conventional cornpressor even if the discharge pressure is increased. The abrasion of the sealing material 5 in contact with the surface of the rotor 3, therefore, is considerably decreased and controlled. Furthermore, since the compressed air having accordingly an increased temperature is also cooled by contact with the surface of the rotor 3 reduction and lowering of the temperature of the discharged air is achieved.

In accordance with experiments in which the present invention was tested, it was found that the average abrasion rate of a carbon sealing material 5 was remarkably reduced to 0.05 mm from 0.39 mm per 200 hours of operation and the temperature of the discharged air was lowered to 164C from 180C in an oilfree air compressor having a 200 mm cylinder internal said housing enclosing the extended edge of said bore and forming a chamber therewith,

said rotor being bored axially from said one end,

a cooling agent injection pipe fixed to said housing and extending within said rotor bore and forming with said rotor bore an annular coolant flow passage opening into said chamber, and

a cooling agent discharge pipe connected to said housing and open to said chamber,

whereby; cooling of said rotor in the vicinity of said peripheral contact with said carbon sealing member reduces the average abrasion rate of said carbon sealing member about eight fold. 

1. An oscillation type compressor comprising: a fixed compressor housing defining an axial bore, a cylindrical rotor having integral vanes extending radially from the periphery thereof in sealing contact with said housing axial bore, bearing means at opposed ends of said Housing for rotatably mounting said rotor for oscillation about the axis thereof, at least one carbon sealing member fixedly carried by each valve seat and being in rubbing contact with said oscillating rotor periphery thereof immediate of said vanes, said housing enclosing the extended edge of said bore and forming a chamber therewith, said rotor being bored axially from said one end, a cooling agent injection pipe fixed to said housing and extending within said rotor bore and forming with said rotor bore an annular coolant flow passage opening into said chamber, and a cooling agent discharge pipe connected to said housing and open to said chamber, whereby; cooling of said rotor in the vicinity of said peripheral contact with said carbon sealing member reduces the average abrasion rate of said carbon sealing member about eight fold. 